JP3418702B2 - Horizontal electric field type liquid crystal display - Google Patents

Horizontal electric field type liquid crystal display

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Publication number
JP3418702B2
JP3418702B2 JP34328998A JP34328998A JP3418702B2 JP 3418702 B2 JP3418702 B2 JP 3418702B2 JP 34328998 A JP34328998 A JP 34328998A JP 34328998 A JP34328998 A JP 34328998A JP 3418702 B2 JP3418702 B2 JP 3418702B2
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Japan
Prior art keywords
lower substrate
liquid crystal
electrode
bus line
electric field
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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JP34328998A
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Japanese (ja)
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JPH11242233A (en
Inventor
升 ▲ヒ▼ 李
香 律 金
Original Assignee
ヒュンダイ ディスプレイ テクノロジー インコーポレイテッド
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Priority to KR1019970065588A priority Critical patent/KR100265572B1/en
Priority to KR1997/P65588 priority
Application filed by ヒュンダイ ディスプレイ テクノロジー インコーポレイテッド filed Critical ヒュンダイ ディスプレイ テクノロジー インコーポレイテッド
Publication of JPH11242233A publication Critical patent/JPH11242233A/en
Application granted granted Critical
Publication of JP3418702B2 publication Critical patent/JP3418702B2/en
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Classifications

    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1343Electrodes
    • G02F1/134309Electrodes characterised by their geometrical arrangement
    • G02F1/134363Electrodes characterised by their geometrical arrangement for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
    • GPHYSICS
    • G02OPTICS
    • G02FDEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH IS MODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THE DEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY, COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g. SWITCHING, GATING, MODULATING OR DEMODULATING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating, or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1337Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133707Structures for producing distorted electric fields, e.g. bumps, protrusions, recesses, slits in pixel electrodes

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (liqui).
d crystal display (LCD), more specifically,
The present invention relates to a liquid crystal display device having an electric field horizontal to the surface of a substrate.

[0002]

2. Description of the Related Art In recent years, LCDs have characteristics such as light weight, thin shape, and low power consumption, and are used in terminals of various information equipments or video equipments. Typical driving methods for such LCDs are TN (twisted nematic) and STN (super
There is a drive system of twisted nematic mode. However, TN-LCDs and STN-LCDs currently in practical use
Has a problem that the viewing angle is very narrow. In order to solve such a problem, IPS-L described next
A CD has been proposed.

In this IPS-LCD, as shown in FIG. 1, a large number of gate bus lines 11 are arranged on the lower insulating substrate 10 in parallel to each other in the x direction, and a large number of data bus lines 15 are arranged in the x direction. Are arranged substantially parallel to each other in the y-direction, which is substantially vertical to define a unit pixel space. At this time,
In the figure, a pair of gate bus lines 11 and a pair of data bus lines 15 are shown in order to show one unit pixel space. Here, the gate bus line 11 and the data bus line 15 are insulated by sandwiching a gate insulating film (not shown).

The counter electrode 12 has a unit pixel space
For example, each is formed to have a rectangular frame shape.
The counter electrode 12 is arranged on the same plane as the gate bus line 11.

The pixel electrode 14 is formed in each unit pixel space in which the counter electrode 12 is formed. The pixel electrode 14 includes a web portion 14a that divides a region surrounded by the rectangular frame-shaped counter electrode 12 in the y direction, and a web portion 14a.
Flange portion 14b connected to one end of the counter electrode 12 in the x direction and overlapping with the counter electrode 12 portion in the x direction, and connected to the other end of the web portion 14a while being parallel to the first flange portion 14b, and the counter electrode 12 portion in the x direction. And a second flange portion 14c that overlaps. That is, the pixel electrode 14 has an "I" shape. Here, the pixel electrode 14 and the counter electrode 12 are insulated by a gate insulating film (not shown).

The thin film transistor 16 is arranged at the intersection of the gate bus line 11 and the data bus line 12. The thin film transistor 16 is connected to the gate bus line 1
1 includes a gate electrode extending from the data bus line 15, a drain electrode extending from the data bus line 15, a source electrode extending from the pixel electrode 14, and a channel layer 17 formed on the gate electrode. The auxiliary capacitor (Cst) is
The counter electrode 12 and the pixel electrode 14 are formed in the overlapping portion.

Although not shown in FIG. 1, the upper substrate provided with the color filters is arranged on the lower substrate 10 so as to face each other with a predetermined distance. In addition, the lower substrate 10
A liquid crystal layer including liquid crystal molecules is interposed between the upper substrate and the upper substrate.

A horizontal alignment layer (not shown) is formed on the upper substrate of the lower substrate and on the inner surface of the upper substrate, respectively, and before an electric field is formed between the counter electrode 12 and the pixel electrode 14. The liquid crystal molecules 19 determine the arrangement direction while being arranged in parallel with the substrate. From the figure, the “R” direction is the rubbing axis direction of the horizontal alignment film formed on the lower substrate.

A first polarizing plate (not shown) is disposed on the outer surface of the lower substrate 10, and a second polarizing plate is disposed on the outer surface of the upper substrate (not shown).
A polarizing plate (not shown) is arranged. Here, the polarization axis of the first polarizing plate is arranged parallel to the "P" direction from the figure. That is, the rubbing axis direction (R) of the alignment film and the polarization axis (P) are parallel to each other. On the other hand, the polarization axis of the second polarizing plate is arranged parallel to the "Q" direction which is substantially perpendicular to the polarization axis of the first polarizing plate.

In such an IPS-LCD, when a scanning signal is applied to the selected gate bus line 11 and a display signal is applied to the data bus line 15, the scanning signal is applied to the gate bus line 11 and the display. The thin film transistor 16 at the intersection with the data bus line 15 to which the signal is applied is turned on. Accordingly, the display signal on the data bus line 15 is transmitted to the pixel electrode 14 through the thin film transistor 16. Therefore, an electric field (E) is generated between the counter electrode 12 and the pixel electrode 14 to which the common signal is applied. At this time, electric field (E)
Is in the "x" direction as shown in the figure, and therefore forms a predetermined angle with the rubbing axis (R).

Therefore, the molecules in the liquid crystal layer are aligned such that the major axis thereof is parallel to the substrate surface and coincides with the major axis of the rubbing direction (R) before the electric field is formed. As a result, the light that has passed through the first polarizing plate and the liquid crystal layer cannot pass through the second polarizing plate, and the screen becomes dark.

On the other hand, when the electric field (E) is formed, the long axis (or optical axis) of the liquid crystal molecules is rearranged in parallel with the electric field (E), and the incident light passes through the second polarizing plate. Therefore, the screen is in a white state.

At this time, the liquid crystal molecules change only in the direction of the long axis of the liquid crystal molecules while being parallel to the substrate surface depending on whether or not an electric field is formed, so that the viewing angle is improved.

[0014]

However, as is well known, the liquid crystal molecules in the liquid crystal have a refractive index anisotropy (Δn) which is different from that of the major axis and the length of shortening. The refractive index anisotropy (Δn) changes depending on the direction. As a result, the polar angle is around 0 ° and the azimuth angle is 0 °, 90 °, 180 °.
At around 270 °, a predetermined hue can be seen despite the white state. Such a phenomenon is called color shift, and this color shift can be explained by the following expression 1. T: transmittance T 0 : transmittance for reference light χ: angle formed by the optical axis of liquid crystal molecules and the polarization axis of the polarizing plate Δn: refractive index anisotropy d: distance or gap between upper and lower substrates (liquid crystal layer Thickness) λ: Wavelength of incident light According to the above formula 1, χ should be π / 4 or Δnd / λ should be π / 2 in order to obtain the maximum transmittance (T). At this time, when Δnd changes (because the refractive index anisotropy value of the liquid crystal molecules changes depending on the viewing direction), the λ value changes to satisfy π / 2. Accordingly, the hue corresponding to the changed light wavelength (λ) appears on the screen.

Therefore, in the direction (a, c) viewed toward the shortening of the liquid crystal molecules, the wavelength of the incident light for reaching the maximum transmittance becomes relatively shorter as Δn decreases. This causes the user to see a blue color with a wavelength shorter than the white wavelength.

On the other hand, in the direction (b, d) viewed toward the contraction of the liquid crystal molecules, the wavelength of the incident light becomes relatively long as Δn increases. This causes the user to see a yellow color with a wavelength longer than that of white. As a result, the image quality characteristics of the IPS-LCD deteriorate.

The present invention was devised to solve the above problems, and an object of the present invention is to provide a liquid crystal display device capable of preventing the color shift phenomenon and improving image quality characteristics. To do.

[0018]

In order to achieve the above-mentioned object of the present invention, the present invention provides a number of parallel data bus lines and the data bus lines which are arranged in parallel so as to form unit pixels in a matrix shape. A lower substrate including a plurality of arranged gate bus lines, a thin film transistor provided at an intersection of a gate bus line and a data bus line in each unit pixel, a pixel electrode connected to the thin film transistor, and a counter electrode. An upper substrate facing the lower substrate at a predetermined distance; a liquid crystal layer interposed between the lower substrate and the upper substrate; and a polarizing plate attached to an outer surface of the lower substrate and an outer surface of the upper substrate, respectively. Each unit pixel defined by the adjacent two gate bus lines and the adjacent two data bus lines has a counter electrode and a pixel electrode. Divided into several electric field space by the Trip field in each of the field forming space is the divided
The angle of inclination with respect to the gate bus line
None, the gate bus line in each unit pixel
Direction and the data bus line direction are line-symmetrical .

Further, according to the present invention, a large number of parallel data bus lines, a large number of gate bus lines arranged in parallel so as to form a matrix-shaped unit pixel with the data bus line, and a gate in each unit pixel. A lower substrate including a thin film transistor provided at an intersection of a bus line and a data bus line, a pixel electrode connected to the thin film transistor, and a counter electrode; an upper substrate facing the lower substrate at a predetermined distance; A liquid crystal layer interposed between the substrate and the upper substrate; horizontal alignment films formed on the inner surface of the lower substrate and the inner surface of the upper substrate; and attached to the outer surface of the lower substrate and the outer surface of the upper substrate, respectively. The counter electrode of the lower substrate includes a polarizing plate, and the counter electrode of the lower substrate has a square frame-shaped first electrode and a space surrounded by the first electrode, and has a plurality of square openings. To separate, it includes a second electrode of a number of parallel gate bus lines, and a common signal line for transmitting a common signal to the first electrode, the pixel electrode of the lower substrate,
A first branch parallel to a data bus line that divides a space surrounded by the first electrode, and several first branches that intersect the first branch and divide each of the opening spaces into four square electric field forming spaces. 2 branches, the direction of the electric field in each of the divided electric field forming spaces is
Make a predetermined inclination angle with respect to the bus line,
Within the unit pixel, the gate bus line direction / data bus
It is characterized by being line-symmetric with respect to both of the sling directions .

Further, according to the present invention, a large number of parallel data bus lines, a large number of gate bus lines arranged in parallel with the data bus lines to form a matrix-shaped unit pixel, and a gate in each unit pixel. A lower substrate including a thin film transistor provided at an intersection of a bus line and a data bus line, and a pixel electrode and a counter electrode connected to the thin film transistor; an upper substrate facing the lower substrate at a predetermined distance; And a liquid crystal layer interposed between the upper substrate; a first horizontal alignment film formed on the inner surface of the lower substrate and having a rubbing axis parallel to the gate bus lines (or data bus lines); and an inner surface of the upper substrate. A second horizontal alignment layer formed on the first horizontal alignment layer and having a rubbing axis that forms a 180 ° angle with the rubbing axis of the first horizontal alignment layer; Is disposed on a side surface, a first polarizing plate having a rubbing axis parallel to the polarization axis of the first horizontal alignment film;
And a second polarizing plate disposed on the outer surface of the upper substrate and having a polarization axis intersecting with the polarization axis of the first polarizing plate,
The counter electrode of the lower substrate has a rectangular frame-shaped first electrode, and a plurality of second parallel electrodes parallel to the gate bus line that divide the space surrounded by the first electrode into several square-shaped opening spaces.
An electrode and a common signal line for transmitting a common signal to the first electrode, wherein the pixel electrode of the lower substrate has a first branch parallel to a data bus line dividing a space surrounded by the first electrode; A plurality of second branches that divide the respective opening spaces into four square electric field forming spaces while intersecting the first branches, and the direction of the electric field in each of the divided electric field forming spaces is Gate bus line
Within a predetermined tilt angle with respect to each of the unit pixels
In the gate bus line direction / data bus line direction
It is characterized by being line-symmetric with respect to both .

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. First, referring to FIGS. 2 and 3, the lower substrate 20 and the upper substrate 40 face each other with a predetermined distance (d: cell gap). The lower substrate 20 and the upper substrate 40 are insulating substrates made of a transparent material, and the cell gap (d) is 6 μm or less, preferably 4 to
It is about 4.5 μm. Lower substrate 20 and upper substrate 40
A few liquid crystal layers 50 containing liquid crystal molecules 50a are interposed therebetween. Here, the liquid crystal molecules 50a in the liquid crystal layer 50 are
It has a dielectric anisotropy (Δε) and a refractive index anisotropy (Δn). For the dielectric anisotropy (Δε), a positive or negative substance is selectively used, and the refractive index anisotropy (Δn) ) Is a positive substance is used. At this time, the refractive index anisotropy (Δn) of the liquid crystal molecule is selected in consideration of the cell gap (d).
0a refractive index anisotropy (Δn) times cell gap (d)
(Phase delay value) should be 0.2 to 0.6.

As shown in FIG. 3, a plurality of gate bus lines 21 extending in the x direction are formed on the lower substrate 20.
And a large number of data bus lines 22 extending in the y direction intersect with each other to limit a unit pixel (sub pixel: p). In the figure, only a pair of gate bus lines 21 and a pair of data bus lines 22 are shown. Gate bus line 2
1 and the data bus line 22 have a gate insulating film (not shown)
It is insulated by sandwiching.

The counter electrode 24 is arranged in each unit pixel (sub pixel) of the lower substrate 20. At this time, the counter electrode 24 has a first electrode 24a having the same reduced shape with respect to the unit pixel (P), and a large number of second electrodes 24b dividing a space surrounded by the first electrode 24a into a predetermined number. including. Here, the second electrode 24b divides the space surrounded by the first electrode 24a into several square spaces. The square space defined by the first and second electrodes 24b is called an opening space (ap). In the present embodiment, the second
The number of electrodes 24b is two, and the number of opening spaces (ap) is three. In addition, the common signal line 240 is the first electrode of the counter electrode 24.
The common signal is transmitted to the counter electrode 24 by being contacted with a predetermined portion of the electrode 24a.

The pixel electrode 25 is also arranged in the unit pixel (P) of the lower substrate 20. The pixel electrode 25 has a first branch 25a in the y direction that bisects the opening space (ap) in parallel with the data bus line 15 in the y direction, and a second branch that intersects the first branch 25a and takes the x direction. Branch 25
b and are included. Here, the first and second branches 25a, 2
5b is arranged so that one opening space (ap) is divided into several square electric field forming spaces. In this embodiment, like the first and second branches 25a and 25b, one opening space (ap) is divided into four electric field forming spaces (AP) having a square shape. Therefore, according to the arrangement of the pixel electrodes 25, the space surrounded by the first electrode 24a is divided into 12 electric field forming spaces (AP) having a square shape.

Here, the counter electrode 24 and the pixel electrode 2
A gate insulating film is interposed between the five. At this time, an auxiliary capacitance capacitance is formed at a portion where the counter electrode 24 and the pixel electrode 25 overlap.

A thin film transistor 27 is provided as a switching device at the intersection of the gate bus line 21 and the data bus line 22. Here, the thin film transistor 27 includes a gate electrode of the gate bus line 21, a drain electrode extending from the data bus line 22 by a predetermined portion,
It includes a source electrode extending from the pixel electrode 25 and a channel layer 27 a disposed above the gate bus line 21.

The first and second alignment layers 30 and 42 are formed on the inner surface of the lower substrate 20 and the inner surface of the upper substrate 40, respectively. Here, the first and second alignment films 30 and 42 are
It is a horizontal alignment film having a pretilt angle of 6 ° or less.
The rubbing axis (r1) of the first alignment film 30 formed on the lower substrate 20 is parallel to the x direction or the y direction. In the present embodiment, the rubbing axis (r1) of the first alignment film 30 is x
Take a direction. Meanwhile, the rubbing axis (r2) of the second alignment film 42 formed on the upper substrate 40 forms an angle of about 180 ° with the rubbing axis (r1) of the first alignment film 30.

The first polarizing plate 35 is arranged on the outer surface of the lower substrate 20, and the second polarizing plate 45 is arranged on the outer surface of the upper substrate 40. The polarization axis of the first polarizing plate 35 is arranged parallel to the rubbing axis (r1) of the first alignment film, and the second polarizing plate 45
The polarization axis of is arranged so as to be perpendicular to the polarization axis of the first polarizing plate 35.

The operation of the liquid crystal display device according to the present invention having the above structure will be described. First, before an electric field is formed between the counter electrode 24 and the pixel electrode 25, the long axes of the liquid crystal molecules are affected by the first and second alignment films 30 and 42 and the surfaces of the upper and lower substrates 20 and 40. Arranged in parallel. At this time,
The long axis of the liquid crystal molecule 50a is parallel to the rubbing axis (r1) of the first alignment film 30. As a result, the light that has passed through the first polarizing plate 35 from the backlight does not change its polarization state while passing through the liquid crystal layer 50. Therefore, the light passing through the liquid crystal layer 50 is absorbed by the second polarizing plate 45 having a polarization axis orthogonal to the polarization axis of the first polarizing plate 35, and the screen becomes dark.

On the other hand, when the gate bus line 21 is selected and the display signal is transmitted to the data bus line 22, the thin film transistor 27 located at the intersection of the gate bus line 21 and the data bus line 22 is turned on. As a result, the display signal of the data bus line 22 is transmitted to the pixel electrode 25, and an electric field (E) is formed between the counter electrode 24 and the pixel electrode 25 to which the common signal is applied.

The electric field at this time (E) is, as shown in FIGS. 3 and 4, Oite within the divided open space of square with each electric field space (AP), the direction of the electric field, The above
A predetermined inclination angle is formed with respect to the gate bus line. Such an electric field type is referred to as an effective electric field (effect fi).
eld), which means an electric field formed between electrodes located at the shortest distance. That is, as shown in FIG. 4, the effective electric field, the first or second branch 25a of the first electrode 24a and the pixel electrode 25 of the counter electrode 24, the 25b
Is formed and has a predetermined inclination angle with respect to the gate bus line
Make up .

At this time, since the electric field forming space (AP) is a square, the effective electric field (E) is applied to the gate line.
The tilt angle is about ± 45 °. As a result, the liquid crystal display device has the maximum transmittance. That is, according to the above equation 1,
The maximum transmittance is obtained when χ is π / 4 (45 °) and Δnd / λ is 1/2. At this time, in the present embodiment, Δn
d / λ is adjusted to 1/2 by adjusting the type of liquid crystal molecules and the cell gap, and χ is the counter electrode 24 and counter so that the electric field direction is ± 45 ° with the y axis (direction of the polarization axis). The maximum transmittance is obtained by designing the electrode 25.

That is, when the liquid crystal molecules 50a are arranged by the electric field (E), the light incident from the backlight is linearly polarized while passing through the polarization axis of the first polarizing plate 35. Then, while passing through the liquid crystal layer 50, the linearly polarized light and the optical axis of the liquid crystal molecule form a predetermined angle,
The polarization state changes. Therefore, since the light whose polarization state has changed passes through the polarization axis of the second polarizing plate 45, the screen becomes white. At this time, since the polarization axes of the first and second polarizing plates 35 and 45 and the long axis of the liquid crystal molecule 50 make an angle of ± 45 °, the maximum transmittance is obtained.

Further, the arrangement of the electrodes 24, 25 as described above, the symmetrical 4 directions to each of the open space (ap), the predetermined inclination angle with respect to the gate bus line
Since an electric field is formed, liquid crystal molecules are arranged in four groups in one opening space (ap). Therefore, 4-domains of liquid crystal molecules are constructed in the unit pixel (P).

As a result, in the white state, even if the user looks at the screen at a certain azimuth angle, the long axis and shortening of the liquid crystal molecules can be seen at the same time. Therefore, the refractive index anisotropy of the liquid crystal molecules is compensated and the color shift does not occur.

FIG. 5 shows the contrast ratio according to the viewing angle of the liquid crystal display device of the present invention. Since the liquid crystal molecules of the present invention are driven by a parallel field, the contrast ratio (CR) is 50 at most azimuth angles. The above is shown and the contrast ratio is 5
The region of 0 or more has mirror symmetry. In addition, the viewing angle characteristics in the direction corresponding to the polarization axis, that is, 0 °, 90 °, 180 °, and 270 ° are more excellent.

Naturally, the present invention can be variously modified and implemented without departing from the scope of the invention.

[0038]

The present invention as described above, according to the present invention is, in the unit pixel space, form a predetermined inclination angle with respect to the polarization axis field, the counter electrode and the pixel electrodes to be more undesirable diagonal electric field is formed With the arrangement, multi-domains of liquid crystal molecules are formed and the color shift phenomenon of the IPS-LCD is improved.

Also, since the liquid crystal molecules are operated by the parallel field, the viewing angle characteristics are excellent, and the polarization axis of the polarizing plate is 0 in particular.
Since it is in the ゜ (180 ゜) and 90 ゜ (270 ゜) directions, 0
The viewing angles in the azimuths of °, 90 °, 180 ° and 270 ° are excellent.

[Brief description of drawings]

FIG. 1 is a plan view of a conventional IPS-LCD.

FIG. 2 is a perspective view of a horizontal electric field type liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a plan view of a lower substrate of a liquid crystal display device according to an exemplary embodiment of the present invention.

FIG. 4 is a plan view showing an electric field forming space of FIG.

FIG. 5 is a diagram showing a curve representing a contrast ratio according to a viewing angle of a liquid crystal display device according to an embodiment of the present invention.

[Explanation of symbols]

10, 20 Lower substrate 11, 21 Gate bus line 12, 24 Counter electrode 14, 25 pixel electrodes 15,22 Data bus line 16, 27 thin film transistor 17, 27a Channel layer 24a First electrode of counter electrode 24b Second electrode of counter electrode 25a First branch of pixel electrode 25b Pixel electrode second branch 30 First alignment film 35 First Polarizing Plate 40 upper substrate 42 Second alignment film 45 Second polarizing plate 240 common electrode wire

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-9-105908 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) G02F 1/1343 G02F 1/1368

Claims (9)

(57) [Claims]
1. A large number of parallel data bus lines, a large number of gate bus lines arranged in parallel so as to form a matrix-shaped unit pixel with the data bus lines, and a gate bus line in each unit pixel. And a data bus line, and a lower substrate including a thin film transistor provided at an intersection of the data bus line and a pixel electrode and a counter electrode connected to the thin film transistor; an upper substrate facing the lower substrate at a predetermined distance; A liquid crystal layer interposed between the substrates; horizontal alignment films formed on the inner surface of the lower substrate and the inner surface of the upper substrate; and polarizing plates attached to the outer surface of the lower substrate and the outer surface of the upper substrate, respectively. The counter electrode of the lower substrate includes a first electrode having a rectangular frame shape and a space surrounded by the first electrode, which is divided into a plurality of square-shaped opening spaces. That the gate bus line and parallel to a plurality of second
An electrode and a common signal line for transmitting a common signal to the first electrode, wherein the pixel electrode of the lower substrate has a first branch parallel to a data bus line dividing a space surrounded by the first electrode;
And a several second branch dividing the open space into four square of the electric field forming space square of each said while crossing with the first branch, the divided field in each of the field formed in space direction
However, the angle of inclination with respect to the gate bus line
The gate bus line direction within each unit pixel
Data for both the bus line direction forms a line symmetry this <br/> a horizontal electric field type liquid crystal display device according to claim.
2. The horizontal alignment layer of the lower substrate has a rubbing axis parallel to the gate bus line, and the horizontal alignment layer of the upper substrate has a rubbing axis of 180 ° with the rubbing axis of the horizontal alignment layer of the lower substrate.
° and having a rubbing axis forming the claim 1
The horizontal electric field type liquid crystal display device described.
3. The polarizing plate disposed on the outer surface of the lower substrate, wherein the polarizing axis of the polarizing plate disposed on the outer surface of the lower substrate is disposed parallel to the rubbing axis of the horizontal alignment film of the lower substrate. 3. The horizontal electric field type liquid crystal display device according to claim 2 , wherein the polarization axis of is arranged so as to intersect with the polarization axis arranged on the outer surface of the lower substrate.
4. The horizontal alignment layer of the lower substrate has a rubbing axis parallel to the data bus lines, and the horizontal alignment layer of the upper substrate has a rubbing axis of 18 with the rubbing axis of the horizontal alignment layer of the lower substrate.
A rubbing shaft having an angle of 0 ° is provided.
1. The horizontal electric field type liquid crystal display device according to 1.
5. The polarizing plate disposed on the outer surface of the upper substrate, wherein the polarizing axis of the polarizing plate disposed on the outer surface of the lower substrate is disposed parallel to the rubbing axis of the horizontal alignment film of the lower substrate. 5. The horizontal electric field type liquid crystal display device according to claim 4, wherein the polarization axis is arranged so as to intersect with the polarization axis arranged on the outer surface of the lower substrate.
First electrode wherein said counter electrode is a horizontal electric field type liquid crystal display device according to claim 1, characterized in that it has the same shape of the reduced-type with respect to the unit pixel.
7. A product of the refractive index anisotropy of the liquid crystal layer thickness Metropolitan of the liquid crystal molecules are horizontally field type liquid crystal display device according to claim 1, wherein from 0.2 to 0.6 .mu.m.
8. A large number of parallel data bus lines, a large number of gate bus lines arranged in parallel to form a matrix-shaped unit pixel with the data bus lines, and a gate bus line in each unit pixel. And a data bus line, and a lower substrate including a thin film transistor provided at an intersection of the data bus line and a pixel electrode and a counter electrode connected to the thin film transistor; an upper substrate facing the lower substrate at a predetermined distance; A liquid crystal layer interposed between the substrates; a first horizontal alignment film formed on the inner surface of the lower substrate and having a rubbing axis parallel to the gate bus lines (or data bus lines); formed on the inner surface of the upper substrate. And the rubbing axis of the first horizontal alignment layer 18
A second horizontal alignment film having a rubbing axis of 0 °; a first polarizing plate disposed on an outer surface of the lower substrate and having a polarization axis parallel to the rubbing axis of the first horizontal alignment film; and the upper substrate. A second polarizing plate having a polarization axis crossing the polarization axis of the first polarizing plate, the counter electrode of the lower substrate having a rectangular frame-shaped first electrode; A large number of second parallel lines parallel to the gate bus lines that divide the space surrounded by the electrodes into several square-shaped opening spaces.
An electrode and a common signal line for transmitting a common signal to the first electrode, wherein the pixel electrode of the lower substrate has a first branch parallel to a data bus line dividing a space surrounded by the first electrode;
A plurality of second electric field forming spaces that divide each of the opening spaces into four square electric field forming spaces while intersecting with the first branch.
A direction of an electric field in each of the divided electric field forming spaces including a branch.
However, the angle of inclination with respect to the gate bus line
The gate bus line direction within each unit pixel
Data for both the bus line direction forms a line symmetry this <br/> a horizontal electric field type liquid crystal display device according to claim.
9. The horizontal electric field type liquid crystal display device according to claim 8 , wherein a product of a refractive index anisotropy of the liquid crystal molecules and a liquid crystal layer thickness is 0.2 to 0.6 μm.
JP34328998A 1997-12-03 1998-12-02 Horizontal electric field type liquid crystal display Expired - Lifetime JP3418702B2 (en)

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